Fortran 90 Handbook

9When there is a current record, the file is positioned at the initial point of therecord, between values in a record, or at the terminal point of the record asillustrated in Figure 9-9....At initial point Between values At ter,minal pointFigure 9-9 Positions within a record of a fileAn internal file is always positioned at the beginning of a record just prior todata transfer.Advancing input/output is record oriented; completion of such an operationalways positions a file at the end of a record or between records, unless anerror condition occurs. In contrast, nonadvancing input/output is characteroriented; after reading and writing, the file may be positioned betweencharacters within the current record.The position of a nonadvancing file is never changed following a data transfer,unless an error, end-of-file, or end-of-record condition occurs while reading thefile. The file position is indeterminate following an error condition whenreading a file.When a nonadvancing input operation is performed, the file can be positionedafter the last character of the file and before the logical or physical end ofrecord. A subsequent nonadvancing input operation causes an end-of-recordcondition to occur, regardless of whether this record is the last record of the354 Fortran 90 HandbookCopyright © 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Wagener